Work in progress shows that the efficiency of radical generation in liposomes is equivalent to that in a homogeneous solvent with macroscopic viscosity of 8 cps. Vitamin E is a less efficient radical trap than BHT in liposomes and the products of phenol oxidation in liposomes are different from those in solution. We now propose to quantitate the effects of phenol concentrations on products to improve material balances and to initiate studies of relative reactivities of antioxidants in lipid bilayers using inhibition of oxidation of methyl linoleate as the absolute measure of reactivity. We then propose to extend these measurements in bilayers to combinations of antioxidants to look for synergistic effects between Vit. E and BHT and between BHT or E and unhindered phenols.